Lung involvement in primary Sjögren's syndrome is mainly related to the small airway disease

To evaluate lung involvement in patients with primary Sjögren's syndrome.

Sixty one consecutive, non-smoking patients, 58 women and three men, were evaluated clinically, physiologically, and radiologically. A bronchial and/or transbronchial biopsy was performed on 13 of the patients. Physiological data were compared with that of a control group of 53 healthy non-smoking subjects matched for age and sex.

In 41% of the patients the main symptom was dry cough. Physiological studies revealed that the patients presented significantly lower expiratory flow values (% pred) when compared with those of the control group: the forced expiratory volume in one second (FEV1) (mean (SD)) was 96% (16) v 111% (13) (p < 0.0001), the maximal expiratory flow at the 50% of the vital capacity (MEF50) was 72% (24) v 103% (17) (p < 0.0001), and the maximal expiratory flow at the 25% of the vital capacity (MEF25) was 49% (25) v 98% (20) (p < 0.0001). No significant difference was noted for the carbon monoxide diffusion value (% pred), between patients and controls. Blood gases were evaluated in 44 patients: mild hypoxemia was observed, and the alveolo-arterial oxygen difference (P(A-a)O2) correlated significantly with MEF50 (r = 0.35, p < 0.01) and MEF25 (r = 0.33, p < 0.01) values. Chest radiography showed mild, interstitial-like changes in 27 patients while slightly increased markings were present in 21. High resolution computed tomography of the lungs was performed in 32 patients (four with a normal chest radiograph, six with suspected interstitial pattern, 19 with apparent interstitial pattern, and three with hyperinflation) and revealed predominantly wall thickening at the segmental bronchi. All positive findings by computed tomography derived from the patients with abnormal chest radiographs. Transbronchial and/or endobronchial biopsy specimens in 10 of the 11 sufficient tissue samples revealed peribronchial and/or peribronchiolar mononuclear inflammation, while interstitial inflammation coexisted in two patients.

The airway epithelia seem to be the main target of the inflammatory lesion of the lung in patients with primary Sjögren's syndrome. It seems to be common, subclinically leading to obstructive small airway physiological abnormalities.